From the lochs of Scotland, and the lakes of Switzerland to the flooded cave systems of Florida, the search for prehistoric man is under way on a global scale. There are over 350 man-made islands, or crannogs, in Scotland alone. Teams of divers are now working their way into the heart of these Bronze Age dwellings. In Switzerland, diving under the ice, archaeologists are revealing the foundations of prehistoric villages: sophisticated communities, where people specialised in pottery and bronze. In a 250-foot-deep sink hole in Florida, a diver discovered human remains. When the skull was brought to the surface, the brain was still intact. It was radiocarbon dated at 11,000 years old. Underwater archaeology is helping to rewrite history books and changing views of prehistoric man.